OBJECTIVE: To examine the intra- and interrater reliability of the Modified Tardieu Scale (MTS) for lower limb assessment of adults with chronic neurologic injuries. DESIGN: Single-center intra- and interrater reliability study. SETTING: Outpatient neurorehabilitation unit. PARTICIPANTS: Adults (N=30; mean age ± SD, 54.1±12.5y) with various chronic neurologic injuries and lower limb spasticity. INTERVENTIONS: Two experienced physiotherapists performed slow (R2) and fast (R1) passive movements for lower limb muscles half an hour apart on the same day (interrater reliability), while a third physiotherapist took goniometric measurements only. One physiotherapist repeated the assessment 1 to 3 days earlier or later (intrarater reliability). Assessors qualitatively rated the resistance to fast passive movements. MAIN OUTCOME MEASURES: Intraclass correlation coefficients (ICCs) and limits of agreement (LOA) were calculated for R1, R2, and R2-R1. Kappa coefficients were calculated for tibialis range of movement and qualitative spasticity ratings. RESULTS: Intra- and interrater R1 and R2 measurements showed moderate to high reliability for the affected hamstrings, rectus femoris, gastrocnemius, soleus (mean ICC ± SD, .79±.08), and tibialis anterior (mean κ ± SD, .58±.10). Only intrarater measurements of the affected tibialis posterior were moderately reliable (R1=.57, R2=.77). Seven of 16 spasticity angle measurements of the affected muscles were moderately reliable. LOA were mostly unacceptably wide. Qualitative spasticity ratings were moderately reliable for affected hamstrings, gastrocnemius, and tibialis muscles (mean κ ± SD, .52±.10). CONCLUSIONS: The MTS is reliable for assessing spasticity in most lower limb muscles of adults with chronic neurologic injuries. Repeated MTS measurements of spasticity are best based on R1 measurements rather than spasticity angle or qualitative ratings of spasticity. Optimally, MTS measurements should be undertaken by the same clinician.